I was noticing that a couple of times on this forum in other discussions about I-295 and I-95, that someone made the suggestion to sign US 1 from I-95/I-295 in Lawrence, NJ for Princeton instead of US 206 to comply with "Princeton" being used as control city along those two interstates. This got me to thinking about other places in New Jersey, especially along I-287, that direct motorists to a nearby city via another road.
Back in 1985, I worked on Campus Drive in Somerset (present day Exit 12 off the I-287) at an office building where I drove one of my female coworkers home who lived in Downtown Somerville. I drove I-287 North to US 22 West. Then exited at North Bridge Street (US 22's only WB exit for Somerville) to pass through the interchange (North Bridge is a pair of right ins and outs at US 22 with a connector road connecting the two discontinuous segments of North Bridge Street together) to Ivanhoe Avenue West to Davenport Street South. Then Davenport to NJ 28 in Downtown Somerville where she had her apartment where NJ 28 deviated from West Main Street. Yet, if you follow the exit guides it has Somerville signed off of I-287 Northbound from Exit 13 for NJ 28 West, with US 22 Westbound signed for Clinton.
It got me thinking about this, as I did use the way I drove her home because it was the fastest and most convenient way to get to her place from that direction of I-287. Therefore just like some of us believe that US 1 in Mercer County is more convenient to reach Princeton than US 206 from I-95/I-295 there despite its signage. I-287 should have US 22 Westbound at Exit 14 signed for Somerville instead of Clinton and replace NJ 28 at Exit 13 with Finderne, a small community of Bridgewater Township, NJ located just west of I-287 from I-287.
One thing about signage along I-287 in New Jersey is its inconsistency as it interchanges with many arteries that connect NYC with far reaches of its metropolitan area, yet some are signed local (particularly the newest section of the freeway north of Boonton), while other are signed regionally. For example NJ 23 in Riverdale is signed inward to NYC area as "Riverdale/ Wayne," but US 22 is signed "New York City." Both are major arterials that lead to the epicenter of the great NYC Metro area, but signed differently from that same interstate freeway. That is in part why Somerville is not mentioned at Exit 14 on the freeway as its part of the regional signing for I-287's signing practice for that area.
I believe that is what happened in the Trenton area, as Princeton was later added to the system as control point for both I-95 and I-295 after control cities were already assigned for exits along those two routes. In both cases I do not think that NJDOT had either Princeton nor Somerville in mind for many motorists as a point of interest so signing the guide signs was just the usual way of using either regional or local points for the connecting roads. Somerville is not directly on US 22 and Princeton is not directly on US 1 either. So nearby interstates crossing would not get them respectively on the exit guides. However, interestingly enough "Somerville" is used on US 22 from local roads connecting with US 22 at other points of US 22 statewide and "Princeton" is indeed used in Trenton on some guides for US 1 NB.